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How Do Plants Have Sex? New Study Reveals All The Details

author

Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockSep 26 2018, 17:18 UTC

The pollen tube emerging from a pollen grain. McGill University

Unless you are a serious dendrophiliac, you might not have wondered how plants reproduce. You might know about pollen and flowers, but not really know the details. Scientists have also been lacking some knowledge but now, a new study gives some insight into just how complex plant sex really is. And there’s even a video.

As reported in the journal Technology, the team were able to look at how plant sperm fertilizes the egg. The sperm is contained in the pollen, while the egg is located in the pistil, which has a long stalk that the sperm must traverse. This is done using the pollen tube, a passageway created by extremely fast-acting cells. This tube is the focus of the new research.

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The team used a “lab-on-a-chip” to study the growth of a pollen tube. Pollen tubes are the fastest-growing cells in the plant kingdom. They can grow between 1 and 2 centimeters (0.4-0.8 inches) every hour and in some cases extend to about 30 centimeters (11.8 inches). The thickness of a pollen tube is equivalent to a fraction of a human hair, but it is capable of exerting high pressure and avoiding obstacles thanks to a feedback mechanism.

“Thanks to the lab-on-a-chip technology we were able to actually see and measure exactly what was going on within the pollen tube as it grew," senior author Professor Anja Geitmann, from McGill University, said in a statement. "We discovered that the water pressure and force that these tiny cells exert as they push through the plant tissue to reach their destination is equivalent to the air pressure we put in our car tires to keep them rolling. 

“What is even more exciting is that we found that when the pollen tube encounters an obstacle, it changes its growth pattern, suggesting that the cells are in some ways able to ‘feel’ and respond to the physical resistance in their environment. It’s very exciting to be able to see this process, and it leaves us with a lot of interesting questions ahead about male-female communication.”

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The study itself required an intriguing feat of engineering. To measure the force exerted by the pollen tube, researchers designed a microscopic cantilever with a gauge built in. The tube had to forcefully push against it to continue its elongation.

The study shows that reproduction in plants is not as simple as one might think, and we are barely scratching the surface of this field. Check out the pollen tube in action in the video below.


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